Decorative film structure and decorative member

ABSTRACT

A decorative film structure includes: a surface layer constituted by a transparent or translucent resin layer; an achromatic layer constituted by dots provided on a back surface of the surface layer; and a metal luster layer provided on the back surface of the surface layer to fill a gap between the dots. As surface roughness of a front surface of the surface layer, an Ra is 2 μm or less and either an Rmax is 4 μm or less or a Sm is 50 μm or more. A lightness L* of the achromatic layer is 0-80. An area of each dot when viewed from a front side of the surface layer is 10 −3 -10 5  μm 2 . A dot area percentage per a unit area when viewed from the front side of the surface layer is 1-80%. A stimulus value Y45° of the metal luster layer is 10000 or more.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Japanese Patent Application No.2011-170172 filed on Aug. 3, 2011, the disclosure of which including thespecification, the drawings, and the claims is hereby incorporated byreference in its entirety.

BACKGROUND

The present disclosure relates to decorative film structures anddecorative members which can be used for interior parts of automobiles,for example.

Automobile interior parts such as door handles are sometimes required tohave metallic design for adding a high quality appearance. As such ametallic design, glossy chromium plating and satin plating having anappearance of oxidized silver are known, for example. However, thechromium plating is too specular to match atmospheres in some automobileinteriors. The satin plating has a quiet texture, but needs to be formedthrough complicated processes.

For this reason, there has been a demand for a technique that can easilyachieve a polished-metallic surface design which is not excessivelyspecular and shines softly. Japanese Patent Publication No. 2009-83183proposes an optical thin-film laminated structure in which an opticalthin film including a light absorption layer made of ahigh-refractive-index thin layer, a low-refractive-index thin layer,and/or a pure metal thin layer is provided on the surface of a basematerial so that the light absorption layer has a metallic luster with asufficiently high reflection lightness and a sufficiently highchromaticness. This technique, however, imparts a metallic luster with ahigh reflection lightness to the base material, and does not impart apolished-metallic surface design with a diminished luster to the basematerial.

SUMMARY

To achieve a polished-metallic surface design which is not excessivelyspecular and shines softly, it is sufficient to obtain a decorative filmstructure having optical properties similar to those of a polished metalsurface and having an appearance with a polished-metallic surfacedesign. For example, the decorative film structure can be easilyobtained by forming multiple layers on a base material of a transferfilm by painting, coating, or other techniques. Alternatively, thedecorative film structure can also be easily obtained by formingmultiple layers on a clear film to serve as the surface layer of thedecorative film structure by painting, coating, or other techniques. Theobtained decorative film structure is transferred or adhered onto thesurface of the base material, thereby easily decorating the surface ofthe base material with a polished-metallic surface design.Alternatively, layers of the decorative film structure may be directlyformed on the surface of the base material by printing, coating, orother techniques.

It is therefore an object of the present disclosure to provide adecorative film structure having optical properties similar to those ofa polished metal surface and having an appearance with apolished-metallic surface design and a decorative member using thedecorative film structure so as to easily achieve a polished-metallicsurface design which is not excessively specular and shines softly.

To achieve the object, a first or a second decorative film structure asdescribed below is provided.

The first decorative film structure includes: a surface layerconstituted by a transparent or translucent resin layer; an achromaticlayer constituted by a plurality of dots provided on a back surface ofthe surface layer; and a metal luster layer provided on the back surfaceof the surface layer to fill a gap between the dots of the achromaticlayer. As surface roughness of the front surface of the surface layer,an arithmetic average roughness Ra is 2 μm or less and either a maximumheight Rmax is 4 μm or less or an average concave to convex distance Smis 50 μm or more. A lightness L* of the achromatic layer in an L*a*b*colorimetric system is 0-80. An area of each of the dots when viewedfrom a front side of the surface layer is 10⁻³-10⁵ μm². A dot areapercentage per a unit area when viewed from the front side of thesurface layer is 1-80%. A stimulus value Y45° of the metal luster layeris 10000 or more. The stimulus value Y45° of the metal luster layer is avalue of Y in tristimulus values of color of an object due to reflectionin an XYZ colorimetric system in a case where an illumination opticalaxis angle is −45°±2° with respect to a direction normal to the frontsurface of the metal luster layer and a received reflected light opticalaxis angle is 45°±2° with respect to a direction normal to the frontsurface of the metal luster layer.

In the above-mentioned configuration, light entering the decorative filmstructure from the side of the surface layer partially causes diffusereflection due to the surface roughness of the front surface of thesurface layer, is partially absorbed in the dots of the achromatic layeron the back surface of the surface layer, and partially causes specularreflection (mirror reflection) by the metal luster layer on the backsurface of the surface layer. In addition, part of the light also causesdiffuse reflection on the peripheries of the dots of the achromaticlayer. The interaction of these light diffuse reflection, lightabsorption, and specular reflection causes the decorative film structureto have optical properties similar to those of a polished metal surfaceand an appearance with a polished-metallic surface design, therebyeasily achieving a polished-metallic surface design which is notexcessively specular and shines softly.

Specifically, as the surface roughness of the front surface of thesurface layer, the arithmetic average roughness Ra is 2 μm or less,thereby ensuring diffuse reflection sufficient for achieving apolished-metallic surface design. Adjustment of the maximum height Rmaxto 4 μm or less or the average concave to convex distance Sm to 50 μm ormore can also ensure diffuse reflection sufficient for achieving apolished-metallic surface design.

The lightness L* of the achromatic layer in the L*a*b* colorimetricsystem (CIE 1976) may be adjusted to 80 or less. This adjustment canensure light absorption sufficient for achieving a polished-metallicsurface design which is not excessively specular and shines softly.

In addition, the area of each of the dots when viewed from the frontside of the surface layer may be adjusted to 10⁻³ μm² or more. Thisadjustment can prevent excessive reduction of the dot size and ensurelight absorption in the dots. On the other hand, the area of each of thedots when viewed from the front side of the surface layer may beadjusted to 10⁵ μm² or less. This adjustment can increase the number ofdots per a unit area with the same dot area percentage (the ratio of thetotal area of all the dots in the unit area to the unit area) whenviewed from the front side of the surface layer. Thus, the totalperipheral length of all the dot in the unit area increases, therebyensuring diffuse reflection on the peripheries of the dots. In addition,it is possible to suppress excessive increase of the dot size, thusreducing degradation of appearance of the decorative film structure.

Furthermore, the dot area percentage per a unit area when viewed fromthe front side of the surface layer may be adjusted to 1% or more. Thisadjustment can ensure light absorption sufficient for achieving apolished-metallic surface design which is not excessively specular andshines softly. On the other hand, the dot area percentage per a unitarea when viewed from the front side of the surface layer may beadjusted to 80% or less. This adjustment can reduce excessive lightabsorption and also reduce excessive decrease in the lightness and/orthe stimulus value of the decorative film structure.

The stimulus value Y45° of metal luster layer may be adjusted to 10000or more. This adjustment can ensure specular reflection (i.e., ametallic luster) sufficient for achieving a polished-metallic surfacedesign.

The second decorative film structure includes: a surface layerconstituted by a transparent or translucent resin layer; an achromaticlayer constituted by a plurality of dots provided on a front surface ofthe surface layer; and a metal luster layer provided on a back surfaceof the surface layer. As surface roughness of the front surface of thesurface layer, an arithmetic average roughness Ra is 2 μm or less andeither a maximum height Rmax is 4 μm or less or an average concave toconvex distance Sm is 50 μm or more. A lightness L* of the achromaticlayer in an L*a*b* colorimetric system is 0-80. An area of each of thedots when viewed from a front side of the surface layer is 10⁻³-10⁵ μm².A dot area percentage per a unit area when viewed from the front side ofthe surface layer is 1-80%. A stimulus value Y45° of the metal lusterlayer is 10000 or more. The stimulus value Y45° of the metal lusterlayer is a value of Y in tristimulus values of color of an object due toreflection in an XYZ colorimetric system in a case where an illuminationoptical axis angle is −45°±2° with respect to a direction normal to thefront surface of the metal luster layer and a received reflected lightoptical axis angle is 45°±2° with respect to a direction normal to thefront surface of the metal luster layer.

In the above-mentioned configuration, light entering the decorative filmstructure from the side of the surface layer partially causes diffusereflection due to the surface roughness of the front surface of thesurface layer, is partially absorbed in the dots of the achromatic layeron the front surface of the surface layer, and partially causes specularreflection (mirror reflection) by the metal luster layer on the backsurface of the surface layer. In addition, part of the light also causesdiffuse reflection on the peripheries of the dots of the achromaticlayer. In the same manner as the first decorative film structure, theinteraction of these light diffuse reflection, light absorption, andspecular reflection causes the decorative film structure to have opticalproperties similar to those of a polished metal surface and anappearance with a polished-metallic surface design, thereby easilyachieving a polished-metallic surface design which is not excessivelyspecular and shines softly.

In the first and second decorative film structures, preferably, as thesurface roughness of the front surface of the surface layer, the Ra is 1μm or less and either the Rmax is 2 μm or less or the Sm is 100 μm ormore.

This configuration can further ensure diffuse reflection sufficient forachieving a polished-metallic surface design.

In the first and second decorative film structures, the lightness L* ofthe achromatic layer is preferably 0-50.

This configuration can further ensure light absorption sufficient forachieving a polished-metallic surface design which is not excessivelyspecular and shines softly.

In the first and second decorative film structures, the dot areapercentage per the unit area when viewed from the front side of thesurface layer is preferably 1-60%.

This configuration can reduce excessive light absorption and also reduceexcessive decrease in the lightness and/or the stimulus value of thedecorative film structure.

In the first and second decorative film structures, the stimulus valueY45° of the metal luster layer is preferably 20000 or more.

This configuration can further ensure specular reflection (metallicluster) sufficient for achieving a polished-metallic surface design.

The first or second decorative film structure may be provided on asurface of a base material, thereby obtaining a decorative memberincluding the base material and a decorative film structure provided onthe surface of the base material.

This configuration allows the decorative member to easily have opticalproperties similar to those of a polished metal surface and anappearance with a polished-metallic surface design.

In the decorative member, the base material is preferably a resin-moldedmember.

This configuration can enhance the flexibility in designing the shape ofthe decorative member.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal sectional view illustrating layeredconfigurations of a decorative film structure and a decorative memberincluding the decorative film structure according to a first exampleembodiment.

FIG. 2 is a longitudinal sectional view illustrating layeredconfigurations of a decorative film structure and a decorative memberincluding the decorative film structure according to a second exampleembodiment.

DETAILED DESCRIPTION

Examples embodiments of the present disclosure will be described indetail hereinafter.

The inventors of the present invention conducted various investigationsto achieve a polished-metallic surface design which is not excessivelyspecular and shines softly by employing a decorative film structure as astack of a plurality of layers. As a result of the investigations, theinventors focused on the fact that diffuse reflection, light absorption,and specular reflection (mirror reflection) of light incident on thedecorative film structure are important factors for achieving apolished-metallic surface design. The inventors also found that diffusereflection can be reproduced by adjusting the surface roughness of thesurface layer of the decorative film structure, light absorption can bereproduced by using an achromatic layer having a relatively lowlightness, and specular reflection can be reproduced by using a metalluster layer with a metallic luster having a relatively large stimulusvalue. The inventors also found that, when the achromatic layer isconstituted by dots as will be described later, diffuse reflection canalso be reproduced by using the peripheries of the dots of theachromatic layer.

However, even when the surface layer is made transparent or translucent,it is difficult to obtain an appearance achieving light diffusereflection, light absorption, and specular reflection by merelylaminating the achromatic layer and the metal luster layer. For example,if the metal luster layer is disposed under the achromatic layer, themetal luster layer hidden by the achromatic layer and is difficult to beseen. Thus, in this case, it is difficult to achieve light specularreflection (i.e., metallic luster). In contrast, if the achromatic layeris disposed under the metal luster layer, the achromatic layer is hiddenby the metal luster layer and is difficult to be seen. Thus, in thiscase, it is difficult to achieve light absorption.

To solve the foregoing problems, the inventors have devised aconfiguration in which an achromatic layer is constituted by a pluralityof dots such that a metal luster layer can be seen through gaps betweenthe dots. The present disclosure has been made based on the foregoingfindings and ideas.

FIG. 1 illustrates a decorative film structure 10 according to a firstexample embodiment. This decorative film structure 10 includes: asurface layer 1 constituted by a transparent or translucent resin layer;an achromatic layer 2 disposed on the back surface (the lower side) ofthe surface layer 1 and constituted by a plurality of dots (minutedots); and a metal luster layer 3 disposed on the back surface (thelower side) of the surface layer 1 to fill the gaps between the dots ofthe achromatic layer 2 and covering the back surface (the lower side) ofthe achromatic layer 2. In the first example embodiment, the surfacelayer 1 has a diffuse reflection function, the achromatic layer 2 has alight absorption function and a diffuse reflection function, and themetal luster layer 3 has a specular reflection function.

In the decorative film structure 10, portions of the metal luster layer3 are located in the gaps between the dots of the achromatic layer 2,resulting in that the metal luster layer 3 can be seen through the gapsbetween the dots when viewed from the front side of the surface layer 1(in plan view). Accordingly, when the decorative film structure 10 isviewed from the side of the surface layer 1 with the diffuse reflectionfunction, minute dots of the achromatic layer 2 with the lightabsorption function are dispersed in the metal luster layer 3 with thespecular reflection function.

In the above-mentioned configuration, light entering the decorative filmstructure 10 from the side of the surface layer 1 partially causesdiffuse reflection due to the surface roughness of the front surface ofthe surface layer 1, is partially absorbed in the dots of the achromaticlayer 2 on the back surface of the surface layer 1, partially causesdiffuse reflection on the peripheries of the dots, and partially causesspecular reflection (mirror reflection) by the metal luster layer 3 onthe back surface of the surface layer 1. The interaction of these lightdiffuse reflection, light absorption, and specular reflection causes thedecorative film structure 10 to have optical properties similar to thoseof a polished metal surface and an appearance with a polished-metallicsurface design, thereby achieving a polished-metallic surface designwhich is not excessively specular and shines softly.

In the decorative film structure 10 illustrated in FIG. 1, the metalluster layer 3 is also disposed on the back surfaces of the dots of theachromatic layer 2, and is present in the gaps between the dots of theachromatic layer 2. However, the present disclosure is not limited tothis example. Alternatively, a configuration in which the metal lusterlayer 3 is not disposed on the back surfaces of the dots of theachromatic layer 2 and is present only in the gaps between the dots ofthe achromatic layer 2 on the back surface of the surface layer 1, maybe employed.

FIG. 2 illustrates a decorative film structure 10 according to a secondexample embodiment. This decorative film structure 10 includes: asurface layer 1 constituted by a transparent or translucent resin layer;an achromatic layer 2 constituted by a plurality of dots (minute dots)provided on the front surface (in a surface portion at the front side)of the surface layer 1; and a metal luster layer 3 disposed on the backsurface of the surface layer 1. The front surface of the achromaticlayer 2 is flush with the front surface of the surface layer 1. In thesecond example embodiment, the surface layer 1 has a diffuse reflectionfunction, the achromatic layer 2 has a light absorption function and adiffuse reflection function, and the metal luster layer 3 has a specularreflection function.

In the decorative film structure 10 illustrated in FIG. 2, the metalluster layer 3 is disposed at the back of the achromatic layer 2,resulting in that the metal luster layer 3 can be seen through the gapsbetween the dots when viewed from the front side of the surface layer 1.Accordingly, when the decorative film structure 10 is viewed from theside of the surface layer 1 with the diffuse reflection function, minutedots of the achromatic layer 2 with the light absorption function aredispersed in the metal luster layer 3 with the specular reflectionfunction.

In the above-mentioned configuration, light entering the decorative filmstructure 10 from the side of the surface layer 1 partially causesdiffuse reflection due to the surface roughness of the front surface ofthe surface layer 1, is partially absorbed in the dots of the achromaticlayer 2 in the front surface of the surface layer 1, partially causesdiffuse reflection on the peripheries of the dots, and partially causesspecular reflection (mirror reflection) by the metal luster layer 3 onthe back surface of the surface layer 1. The interaction of these lightdiffuse reflection, light absorption, and specular reflection causes thedecorative film structure 10 to have optical properties similar to thoseof a polished metal surface and an appearance with a polished-metallicsurface design, thereby achieving a polished-metallic surface designwhich is not excessively specular and shines softly.

In the first and second example embodiments, the diffuse reflectionfunction refers to the function of reflecting 20% or more of theintensity of visible light (wavelength: 420-670 nm, angle of divergence:substantially zero degrees) externally incident at an incident angle of45°, toward directions except for directions within a specularreflection angle of ±3°, in reflecting the visible light, or thefunction of changing the direction of 5% or more of the transmittedlight intensity of visible light (wavelength: 380-780 nm, angle ofdivergence: substantially zero degrees) externally incident at anincident angle of 90°, toward directions except for the directionswithin a specular transmission angle of ±3°, in transmitting the visiblelight.

In the first and second example embodiments, the light absorptionfunction refers to the function of absorbing or transmitting 20% or moreof the intensity of visible light (wavelength: 420-670 nm, angle ofdivergence: substantially zero degrees) externally incident at anincident angle of 90°. In reflecting the incident visible light, thedifference in reflection factor between the wavelengths (420-670 nm) ispreferably within ±10%.

In the first and second example embodiments, the specular reflectionfunction refers to the function of reflecting 90% or more of thereflected light intensity of visible light (wavelength: 420-670 nm,angle of divergence: substantially zero degrees) externally incident atan incident angle of 45°, toward directions within a specular reflectionangle of ±3°, in reflecting the visible light.

In the first and second example embodiments, the surface roughness(specifically, an arithmetic average roughness Ra, a maximum heightRmax, and an average concave to convex distance Sm) of the front surfaceof the surface layer 1, the lightness L* of the achromatic layer 2,which will be described later, the area of each dot of the achromaticlayer 2 when viewed from the front side of the surface layer 1, the dotarea percentage per a unit area (i.e., the ratio of the total area ofall the dots per a unit area to the unit area, hereinafter referred toas a dot area percentage) when viewed from the front side of the surfacelayer 1, and the stimulus value Y45° of the metal luster layer 3, whichwill be described later, are adjusted, thereby adjusting the degree oflight diffuse reflection, the degree of light specular reflection, andthe degree of light absorption to desired values independently of eachother in the decorative film structure 10.

In the first and second example embodiments, as the surface roughness ofthe front surface of the surface layer 1, the arithmetic averageroughness Ra is 2 μm or less, and either the maximum height Rmax is 4 μmor less or the average concave to convex distance Sm is 50 μm or more.Adjustment of the arithmetic average roughness Ra to 2 μm or less canensure diffuse reflection sufficient for achieving a polished-metallicsurface design. Adjustment of the maximum height Rmax to 4 μm or less orthe average concave to convex distance Sm to 50 μm or more can alsoensure diffuse reflection sufficient for achieving a polished-metallicsurface design.

As the surface roughness of the front surface of the surface layer 1, itis more preferable that the Ra is 1 μm or less and either the Rmax is 2μm or less or the Sm is 100 μm or more. This adjustment further canensure diffuse reflection sufficient for achieving a polished-metallicsurface design.

In the first and second example embodiments, the lightness L* of theachromatic layer 2 in an L*a*b* colorimetric system (CIE 1976) is 0-80.Adjustment of the lightness L* of the achromatic layer 2 to 80 or lesscan ensure light absorption sufficient for achieving a polished-metallicsurface design which is not excessively specular and shines softly. Thelightness L* of the achromatic layer 2 is preferably adjusted to 0-50.This adjustment can further ensure light absorption sufficient forachieving a polished-metallic surface design which is not excessivelyspecular and shines softly.

In the first and second example embodiments, the area of each dot whenviewed from the front side of the surface layer 1 is 10⁻³-10⁵ μm².Adjustment of the area of each dot to 10⁻³ μm² or more can preventexcessive reduction of the dot size and ensure light absorption in thedots. On the other hand, adjustment of the area of each dot to 10⁵ μm²or less increases the number of dots per a unit area with the same dotarea percentage. Thus, the total peripheral length of all the dot in theunit area increases, thereby ensuring diffuse reflection on theperipheries of the dots. In addition, it is possible to suppressexcessive increase of the dot size, thus reducing degradation ofappearance of the decorative film structure 10.

In the first and second example embodiments, the dot area percentage is1-80%. Adjustment of the dot area percentage to 1% or more can ensurelight absorption sufficient for achieving a polished-metallic surfacedesign which is not excessively specular and shines softly. Adjustmentof the dot area percentage to 80% or less can reduce excessive lightabsorption and also reduce excessive decrease in the lightness and/orthe stimulus value of the decorative film structure 10.

The dot area percentage of the achromatic layer 2 is more preferably1-60%. This adjustment can reduce excessive light absorption, andfurther reduce excessive decrease in the lightness and/or the stimulusvalue of the decorative film structure 10.

In the first and second example embodiments, the stimulus value Y45° ofthe metal luster layer 3, which is the value of Y in tristimulus values(X, Y, and Z) of color of an object in an XYZ colorimetric system (CIE1931 colorimetric system) in a case where the illumination optical axisangle is −45°±2° and the received reflected light optical axis angle is45°±2° with respect to a direction normal to the front surface of themetal luster layer, is 10000 or more. The adjustment of the stimulusvalue Y45° of the metal luster layer 3 to 10000 or more can ensurespecular reflection (metallic luster) sufficient for achieving apolished-metallic surface design.

The stimulus value Y45° of the metal luster layer 3 is more preferablyadjusted to 20000 or more. This adjustment can further ensure specularreflection (metallic luster) sufficient for achieving apolished-metallic surface design.

In the first and second example embodiments, the thicknesses of thesurface layer 1, the achromatic layer 2, and the metal luster layer 3are not specifically limited. The thickness of each layer can be withinthe range from 1 μm to 1 mm, for example, as necessary.

The surface layer 1 may be colorless or colored as long as the surfacelayer 1 is transparent or translucent. Adjustment of color of thesurface layer 1 makes it possible to select a desired type of a metal(e.g., aluminium) for a polished-metallic surface design of thedecorative film structure 10.

The material for the achromatic layer 2 is not specifically limited. Thematerial for the achromatic layer 2 is preferably a resin or a metal,but may be paper or other fibrous materials, or a mineral or otherinorganic materials, as necessary.

The material for the metal luster layer 3 is not specifically limited,either, and is preferably a resin or a metal, for example. Adjustment ofcolor of the metal luster layer 3 makes it possible to select a desiredtype of a metal (e.g., aluminium) for a polished-metallic surface designof the decorative film structure 10.

In the first and second example embodiments, the decorative filmstructure 10 can be easily obtained by forming the layers 1-3 on a basematerial (not shown) of a transfer film by printing, coating, or othertechniques. Alternatively, the decorative film structure 10 can also beeasily obtained by forming the achromatic layer 2 and the metal lusterlayer 3 on a clear film to be a surface layer 1 of the decorative filmstructure 10 by printing, coating, or other techniques. Then, theobtained decorative film structure 10 is transferred or adhered, forexample, to the surface of a base material 5 (see, FIGS. 1 and 2),thereby easily providing the base material 5 with a polished-metallicsurface. Alternatively, the layers 1-3 of the decorative film structure10 may be directly formed on the surface of the base material 5 byprinting, coating, or other techniques.

In the foregoing manner, a decorative member 20 including the basematerial 5 and the decorative film structure 10 provided on the surfaceof the base material 5 is obtained. This decorative member 20 hasoptical properties similar to those of a polished metal surface, and anappearance with a polished-metallic surface design. The decorativemember 20 can be preferably used for automobile interior parts such asdoor handles, and parts of household appliances, personal computers,cellular phones, office suppliers, sporting goods, measurementequipment, sundry goods, and so on.

The base material 5 is preferably a resin-molded member. This is becausethe flexibility in designing the shape of the decorative member 20having optical properties similar to those of a polished metal surfaceand an appearance with a polished-metallic surface design can beenhanced.

In FIGS. 1 and 2, reference character 4 denotes a backing layer forpushing the metal luster layer 3 against the surface layer 1 and/or anadhesive layer for causing the decorative film structure 10 to adhere tothe base material 5. A protective layer (not shown) for preventing themetal luster layer 3 from being eroded or corroded by the backing layer(and/or the adhesive layer) 4 may be provided between the metal lusterlayer 3 and the backing layer (and/or the adhesive layer) 4.

The present disclosure is not limited to the foregoing exampleembodiments, and various changes and modifications may be made withoutdeparting from the scope of the claims.

For example, a transparent or translucent, colorless or coloredprotective layer may be provided on the front surface of the decorativefilm structure 10 or the front surface of the decorative member 20without impairing advantages of the present disclosure. This protectivelayer can be directly on the front surface of the surface layer 1, forexample. The protective layer is intended to protect the front surfaceof the decorative film structure 10 or the decorative member 20.Alternatively, the protective layer may be intended to adjust thesurface roughness (Ra, Rmax, and Sm) of the front surface of the surfacelayer 1. Accordingly, the surface roughness (Ra, Rmax, and Sm) of thefront surface of the surface layer 1 includes the surface roughness (Ra,Rmax, and Sm) adjusted by using the protective layer.

The example embodiments described above are provided by way ofillustration only and should not be construed to limit the invention.The scope of the invention should be measured solely by reference to theclaims. All the modifications and changes within an equivalent scope ofthe claims fall within the scope of the invention.

The present disclosure will be described more specifically hereinafterthrough examples. However, the present disclosure is not limited to thefollowing examples.

[Formation of Decorative Film Structure]

(Test Numbers 1-10 and 12-14)

Decorative film structures each having a configuration similar to thatof the decorative film structure 10 illustrated in FIG. 1 were formed tomeet the specifications shown in Tables 1 and 2. In Tables 1 and 2, the“average area” in the field of “dot size of achromatic layer” is anaverage area of the dots of an achromatic layer when viewed from thefront side of a surface layer, the “area percentage (%)” in the field ofthe “dot area percentage of achromatic layer” is the ratio of a dot areaper a unit area when viewed from the front side of the surface layer.

Each of the above-mentioned decorative film structures was formed in thefollowing manner. Using a polycarbonate sheet “PC1151” (sheet thickness:0.5 mm) produced by TEIJIN CHEMICALS LTD.) as a surface layer, anachromatic layer (thickness: 3 μm) in the form of dots was formed byscreen printing on this surface layer. The formation of the achromaticlayer employed an UV ink “HUG” produced by Seiko advance Ltd. Then, ametal luster layer (with a thickness of 2 μm on the achromatic layer)was formed by screen printing on the surface layer and the achromaticlayer. The formation of the metal luster layer employed an ink“MIR-51000 Mirror Silver” produced by Teikoku Printing Inks Mfg Co.,LTD. Thereafter, a backing layer (thickness: 10 μm) was formed by screenprinting on the metal luster layer. The formation of the backing layeremployed an ink “MIB-611 White” produced by Teikoku Printing Inks MfgCo., LTD. In this manner, a decorative film structure having anappearance of a polished-like surface of aluminium when viewed from theside of the surface layer was obtained.

(Test Number 11)

A decorative film structure was formed in the same manner as those oftest numbers 1-10 and 12-14 with the exception that no achromatic layerwas formed. The decorative film structure of test number 11 is differentfrom those of the present disclosure.

(Test Numbers 16 and 17)

A decorative film structure was formed in the same manner as those oftest numbers 1-10 and 12-14 with the exception that a high-luminancesilver ink produced by Nippon Bee Chemical Co., LTD. was used in theformation of a metal luster layer. This decorative film structure issimilar to those of test numbers 1-10 and 12-14.

(Test Number 15)

A decorative film structure was formed in the same manner as those oftest numbers 16 and 17 with the exception that no achromatic layer wasformed. The decorative film structure of test number 15 was differentfrom those of the present disclosure.

[Appearance Evaluation of Decorative Film Structure]

The appearance of each of the decorative film structures formed in theforegoing manner was optically evaluated. Specifically, the decorativefilm structure was irradiated with visible light (wavelength: 420-670nm, angle of divergence: substantially zero degrees) at an incidentangle of 45° from the side of the surface layer. Then, the stimulusvalue Y at the specular reflection angle, i.e., the stimulus value Y45°of specular reflection (mirror reflection), and the stimulus value Ywhich is at −5° from the specular reflection angle, i.e., the stimulusvalue Y40° of diffuse reflection, were measured with a multi-anglespectrophotometer. The measurement results are shown in Tables 1 and 2.

Here, the stimulus value Y45° of specular reflection is the value of Yin tristimulus values of color of an object due to reflection in an XYZcolorimetric system in a case where the illumination optical axis angleis −45°±2° and the received reflected light optical axis angle is 45°±2°with respect to a direction normal to a sample surface (i.e., the frontsurface of the surface layer). The stimulus value Y40° of diffusereflection is the value of Y in tristimulus values of color of an objectdue to reflection in an XYZ colorimetric system in a case where theillumination optical axis angle is −45°±2° and the received reflectedlight optical axis angle is 40°±2° with respect to a direction normal toa sample surface (i.e., the front surface of the surface layer).

For comparison, the stimulus value Y45° of specular reflection and thestimulus value Y40° of diffuse reflection of a real polished surface ofaluminium and satin plating (satin nickel plating) were measured in thesame manner. Then, the stimulus value Y45° of specular reflection on thealuminium polished surface was 35000-55000 (e.g., 38306), the stimulusvalue Y40° of diffuse reflection was 900-1300 (e.g., 925), the stimulusvalue Y45° of specular reflection on satin plating was 10000-75000(e.g., 31977), and the stimulus value Y40° of diffuse reflection was900-2600 (e.g., 1784). In addition, the ratio of the diffuse reflectionstimulus value Y40° to the specular reflection stimulus value Y45° onthe aluminium polished surface (Y40°/Y45°) was 0.016-0.037 (e.g.,0.024), and the ratio of the diffuse reflection stimulus value Y40° tothe specular reflection stimulus value Y45° on satin plating (Y40°/Y45°)was 0.012-0.26 (e.g., 0.056).

As compared to the decorative film structures of test numbers 11 and 15where no achromatic layer was formed, the decorative film structures oftest numbers 1-10, 12-14, 16, and 17 showed that the specular reflectionstimulus value Y45°, the diffuse reflection stimulus value Y40°, and/orthe ratio of the diffuse reflection stimulus value Y40° to the specularreflection stimulus value Y45° (Y40°/Y45°) were close to those of thereal aluminium polished surface.

The ratio of the diffuse reflection stimulus value Y40° to the specularreflection stimulus value Y45° (Y40°/Y45°) is preferably in the rangefrom 0.007 to 0.25, both inclusive, more preferably in the range from0.008 to 0.13, both inclusive, and much more preferably in the rangefrom 0.01 to 0.06, both inclusive. If the ratio is too small, the lustertends to be too strong to achieve a texture which shines softly. On theother hand, if the ratio is too large, the luster tends to be too weakwith a texture which shines excessively softly.

The specular reflection stimulus value Y45° is preferably in the rangefrom 4000 to 100000, both inclusive, more preferably in the range from7000 to 75000, both inclusive, and much more preferably 10000 to 50000,both inclusive. If the ratio is too small, the luster tends to be tooweak with an excessive dimness. On the other hand, if the ratio is toolarge, the luster tends to be too bright with an excessive brightness.

In particular, an important factor for achieving a polished-metallicsurface design which is not excessively specular and shines softly isthat the ratio of the diffuse reflection stimulus value Y40° to thespecular reflection stimulus value Y45° (Y40°/Y45°) is not excessivelysmall (e.g., not less than 0.007).

TABLE 1 Test number 1 2 3 4 5 specification surface roughness Ra (μm)0.04 of surface layer Rmax (μm) 0.52 Sm (μm) 32.8 stimulus value of Y45°102092 metal luster layer lightness of L* 5 80 50 25 5 achromatic layerdot size of average area × 7.1 2.5 achromatic layer 10⁴ (μm²) dot areaarea 80 40 percentage of percentage achromatic layer (%) evaluation ofspecular reflection Y45° 14679 52659 44557 45882 40146 appearancestimulus value diffuse reflection Y40° 141 577 506 456 462 stimulusvalue stimulus value Y40°/Y45° 0.0096 0.011 0.011 0.0099 0.012 ratioTest number 6 7 8 9 specification surface roughness Ra (μm) 0.04 ofsurface layer Rmax (μm) 0.52 Sm (μm) 32.8 stimulus value of Y45° 102092metal luster layer lightness of L* 5 achromatic layer dot size ofaverage area × 1.8 1.1 0.8 0.1 achromatic layer 10⁴ (μm²) dot area area30 20 5 percentage of percentage achromatic layer (%) evaluation ofspecular reflection Y45° 59660 77072 78613 91098 appearance stimulusvalue diffuse reflection Y40° 490 574 653 676 stimulus value stimulusvalue Y40°/Y45° 0.0082 0.0074 0.0083 0.0074 ratio

TABLE 2 Test number 10 11 12 13 14 15 16 17 specification surfaceroughness Ra (μm) 0.04 0.2 0.09 0.31 0.04 0.12 0.37 of surface layerRmax (μm) 0.52 4.62 1.62 2.7 0.52 1.14 3.92 Sm (μm) 32.8 605.5 194.581.6 32.8 32.4 501.4 stimulus value of Y45° 102092 17729 metal lusterlayer lightness of L* 5 — 5 — 5 achromatic layer dot size of averagearea × 0.1 — 0.8 — 0.1 achromatic layer 10⁴ (μm²) dot area area 1 0 20 05 percentage of percentage achromatic layer (%) evaluation of specularreflection Y45° 98893 102092 36271 30409 3902 17729 6858 1117 appearancestimulus value diffuse reflection Y40° 701 578 1474 1590 1849 123 916926 stimulus value stimulus value Y40°/Y45° 0.0071 0.0057 0.041 0.0520.47 0.0069 0.13 0.83 ratio

What is claimed is:
 1. A decorative film structure, comprising: asurface layer constituted by a transparent or translucent resin layer;an achromatic layer constituted by a plurality of dots provided on aback surface of the surface layer; and a metal luster layer provided onthe back surface of the surface layer to fill a gap between the dots ofthe achromatic layer, wherein as surface roughness of a front surface ofthe surface layer, an arithmetic average roughness Ra is 2 μm or lessand either a maximum height Rmax is 4 μm or less or an average concaveto convex distance Sm is 50 μm or more, a lightness L* of the achromaticlayer in an L*a*b* colorimetric system is 0-80, an area of each of thedots when viewed from a front side of the surface layer is 10⁻³-10⁵ μm²,a dot area percentage per a unit area when viewed from the front side ofthe surface layer is 1-80%, a stimulus value Y45° of the metal lusterlayer, which is a value of Y in tristimulus values of color of an objectdue to reflection in an XYZ colorimetric system in a case where anillumination optical axis angle is −45°±2° and a received reflectedlight optical axis angle is 45°±2° with respect to a direction normal tothe front surface of the metal luster layer, is 10000 or more, and thedots of the achromatic layer absorb part of light entering thedecorative film structure from the front surface of the surface layerand cause diffuse reflection of part of the light on peripheries of thedots.
 2. The decorative film structure of claim 1, wherein as thesurface roughness of the front surface of the surface layer, the Ra is 1μm or less and either the Rmax is 2 μm or less or the Sm is 100 μm ormore.
 3. The decorative film structure of claim 1, wherein the lightnessL* of the achromatic layer is 0-50.
 4. The decorative film structure ofclaim 1, wherein the dot area percentage per the unit area when viewedfrom the front side of the surface layer is 1-60%.
 5. The decorativefilm structure of claim 1, wherein the stimulus value Y45° of the metalluster layer is 20000 or more.
 6. A decorative film structure,comprising: a surface layer constituted by a transparent or translucentresin layer; an achromatic layer constituted by a plurality of dotsprovided on a front surface of the surface layer; and a metal lusterlayer provided on a back surface of the surface layer, wherein assurface roughness of the front surface of the surface layer, anarithmetic average roughness Ra is 2 μm or less and either a maximumheight Rmax is 4 μm or less or an average concave to convex distance Smis 50 μm or more, a lightness L* of the achromatic layer in an L*a*b*colorimetric system is 0-80, an area of each of the dots when viewedfrom a front side of the surface layer is 10⁻³-10⁵ μm², a dot areapercentage per a unit area when viewed from the front side of thesurface layer is 1-80%, a stimulus value Y45° of the metal luster layer,which is a value of Y in tristimulus values of color of an object due toreflection in an XYZ colorimetric system in a case where an illuminationoptical axis angle is −45°±2° and a received reflected light opticalaxis angle is 45°±2° with respect to a direction normal to the frontsurface of the metal luster layer, is 10000 or more, and the dots of theachromatic layer absorb part of light entering the decorative filmstructure from the front surface of the surface layer and cause diffusereflection of part of the light on peripheries of the dots.
 7. Thedecorative film structure of claim 6, wherein as the surface roughnessof the front surface of the surface layer, the Ra is 1 μm or less andeither the Rmax is 2 μm or less or the Sm is 100 μm or more.
 8. Thedecorative film structure of claim 6, wherein the lightness L* ofachromatic layer is 0-50.
 9. The decorative film structure of claim 6,wherein the dot area percentage per the unit area when viewed from thefront side of the surface layer is 1-60%.
 10. The decorative filmstructure of claim 6, wherein the stimulus value Y45° of the metalluster layer is 20000 or more.
 11. A decorative member, comprising: abase material; and a decorative film structure provided on a surface ofthe base material, wherein the decorative film structure includes asurface layer constituted by a transparent or translucent resin layer;an achromatic layer constituted by a plurality of dots provided on aback surface of the surface layer; and a metal luster layer provided onthe back surface of the surface layer to fill a gap between the dots ofthe achromatic layer, as surface roughness of a front surface of thesurface layer, an arithmetic average roughness Ra is 2 μm or less andeither a maximum height Rmax is 4 μm or less or an average concave toconvex distance Sm is 50 μm or more, a lightness L* of the achromaticlayer in an L*a*b* colorimetric system is 0-80, an area of each of thedots when viewed from a front side of the surface layer is 10⁻³-10⁵ μm²,a dot area percentage per a unit area when viewed from the front side ofthe surface layer is 1-80%, a stimulus value Y45° of the metal lusterlayer, which is a value of Y in tristimulus values of color of an objectdue to reflection in an XYZ colorimetric system in a case where anillumination optical axis angle is −45°±2° and a received reflectedlight optical axis angle is 45°±2° with respect to a direction normal tothe front surface of the metal luster layer, is 10000 or more and thedots of the achromatic layer absorb part of light entering thedecorative film structure from the front surface of the surface layerand cause diffuse reflection of part of the light on peripheries of thedots.
 12. The decorative member of claim 11, wherein the base materialis a resin-molded member.
 13. A decorative member, comprising: a basematerial; and a decorative film structure provided on a surface of thebase material, wherein the decorative film structure includes a surfacelayer constituted by a transparent or translucent resin layer; anachromatic layer constituted by a plurality of dots provided on a frontsurface of the surface layer; and a metal luster layer provided on aback surface of the surface layer, as surface roughness of the frontsurface of the surface layer, an arithmetic average roughness Ra is 2 μmor less and either a maximum height Rmax is 4 μm or less or an averageconcave to convex distance Sm is 50 μm or more, a lightness L* of theachromatic layer in an L*a*b* colorimetric system is 0-80, an area ofeach of the dots when viewed from a front side of the front surface ofthe surface layer is 10⁻³-10⁵ μm², a dot area percentage per a unit areawhen viewed from the front side of the surface layer is 1-80%, and astimulus value Y45° of the metal luster layer, which is a value of Y intristimulus values of color of an object due to reflection in an XYZcolorimetric system in a case where an illumination optical axis angleis −45°±2° and a received reflected light optical axis angle is 45°±2°with respect to a direction normal to the front surface of the metalluster layer, is 10000 or more, and the dots of the achromatic layerabsorb part of light entering the decorative film structure from thefront surface of the surface layer and cause diffuse reflection of partof the light on peripheries of the dots.
 14. The decorative member ofclaim 13, wherein the base material is a resin-molded member.